Arc chute mixing chamber for cooling exiting gases employing a reflective screen arc barrier



Aug. 9, 1966 F. J. POKORNY 3,265,842

ARC CHUTE MIXING CHAMBER FOR COOLING EXITING GASES EMPLOYING A REFLECTIVE SCREEN ARC BARRIER Filed July 18, 1963 5 Sheets-Sheet 1 64 Q :2? J l C I 5% INVENTOR. Fem/z POAO/ZA/ Y Aug. 9, 1966 F PQKQRNY 3,365,842

ARC CHUTE MIXING CI'IAMBER FOR COOLING EXITING GASE V EMPLOYING A REFLECTIVE SCREEN ARC BARRIER Filed July 18, 1963 I 5 Sheets-Sheet 2 INVENTOR. v ,cemvz .1 Fame/w Aug. 9, 1966 F. J. POKORNY 3,265,842 SES ARC CHUTE MIXING CHAMB ER FOR COOLING EXITING GA 9 EMPLOYING A REFLECTIVE SCREEN ARC BARRIER 1 63 5 Sheets-Sheet 3 Filed July 18,

iNVENTOR. :eA/VK J PGKO EA/y Off/exam; 42565 42195 ,4 \I'JFFEA/ 4 True: YS

United States Patent Pennsylvania Filed July 18, 1963, Ser. No. 295,932

2 Claims. (Cl. 200-144) The instant invention relates to circuit interrupters and more particularly to a novel reflective screen arc barrier which so completely dei-onizes and cools escaping gases emitted from the circuit breaker arc chute as to permit the positioning of a grounded roof directly above the arc chute even during an interruption operation thereof.

In circuit breakers of high fault current interrupting capacity one of the main problems confronted during an interruption operation is the de-ionization of gases exhausted from the arc chute in order to prevent the occurrence of a power fault from line to ground or from line to line. The de-ionization problem is extremely acute in circuit breakers of the 3000-4000 ampere and 600 volt capacity.

In order to alleviate this most severe problem, past designs have included the employment of baffle plates in the arc chute for mixing and hence de-ionization of the gases. Other designs have included hood arrangements over the top of the chute or a series of long narrow passages at the exit of the chute. The intent of such structures is that of forcing the vented gases to remain in contact with cooling surfaces until they are substantially de-ionized and further to direct the path of the gases away from grounded or live parts of the circuit breaker structures. Such cooling surfaces have generally been formed of a type of insulating material as opposed to a metallic material which is possessed of high thermal conductivity and hence superior cooling characteristics.

The instant invention provides an arrangement which employs a metallic reflective screen which combines the functions of de-ionization, cooling and deceleration of the exiting gases so as to render gases emitted from the top of the arc chute incapable of causing a line to ground or line to line fault.

The instant invention is comprised of an arc chute having spaced parallel plates for the purpose of providing a tortuous path for an upwardly moving arc. The are plates are of a conductive material to provide the dual functions of acting as an extremely good cooling medium for an upwardly moving arc and further for setting up a magnetic field to rapidly urge the arc in the upward direction. A plurality of mixing chambers, each partitioned off from the other by a plurality of insulating members, are provided immediately above the main interrupting chamber containing the spaced parallel arc plates for the purpose. of mixing the rising gases in order to de-ionize the gases. A third chamber is provided immediately above the mixing chamber, which third chamber is further compartmentalized by insulating members; The third chamber is provided with a corrugated metallic screen having a plurality of ridges arranged so as to be in the direct path of upwardly rising gases. The third chamber is further provided with upper and lower baflle plates which are so arranged as to have openings to cause the gases to come in contact with the diagonal portions of the reflective screen barrier and not with the vertexes of the corrugated screen arrangement. This causes the gases to make contact with an extremely large metallic screen surface area so as to rapidly cool the exiting gases. In addition thereto, no path whatsoever is provided to permit the gases to move directly in the upward vertical "ice direction, but on the contrary, the reflective screen causes the gases to move in a diagonal direction through the reflective screen before moving upward and out of the reflective screen chambers. By the time the gases exit through the openings of the upper baflie plate, the gases are so thoroughly cooled and de-ionized as to be powerless to permit any restrike of the arc. The de-ionization operation performed by the mixing and reflective screen chambers is so efficient that a grounded metallic roof may be placed directly above the arc chute and be so close in proximity thereto as to allow only for mechanical clearance, thus permitting a compartment for the circuit breaker to have overall dimensions substantially diminished from those of prior art compartments which require substantially more room between the upper end of the arc chute and the compartment roof.

A second novel feature of the instant invention is the provision of an arc chute assembly which is essentially two are chutes arranged in parallel, each arc chute having its own set of metallic arc plates, baffle members and reflective screen cooling members. The first and second arc chute sub-assemblies are combined in one shell in such a way that there is communication between these subassemblies through an opening provided in the center wall. Each of said are chutes is associated witha pair of cooperating main and arcing contacts for which each arc chute is designed to extinguish the are which may beformed by its associated arcing contacts. The first and second contact sets are arranged to'be in electrical parallel and are. further arranged to move to the engaged and disengaged positions in synchronism. Since absolutely perfect synchronism is not possible, it is therefore evident that one set of cooperating arcing contacts will separate slightly before the other set of arcing contacts. For low current interruptions the arrangement may cause an arc to be struck in only one of the two are chute sections; namely, that arcchute section in which the cooperating arcing contacts have separated last. The communication between the first and second arc chute sections, however, causes a movement of the deionized gases from the section interrupting the are into the section in which no arc is formed, thus aiding the exiting, deionization and cooling of the escaping gases by sharing the interrupting burden equally between the interrupting means. During such low current interruptions, the section in which the arc is struck is only randomly determined since no deliberate design has been provided to cause one set of arcing contacts to open before the other. Thus, the actual section which interrupts the arc occurs in a random fashion.

At higher current levels even though one of the two sets of arcing contacts may open before the other, the ionized gases which 'are formed are so intense as to be forced from the chamber in which the arc is struck into the second chamber causing an arc to be struck in this chamber as well. Thus, the interruption is spread into both sections, and half the capacity of the electric current arc is shared by both sections. Therefore, the mixing chamber and the reflective screen barrier chamber of each arc chute section provide a simple and effective deionizing medium for exiting gases, and the multi-section arc chute provides a compact arrangement for the interruption of extremely high capacity are currents.

It is therefore one object of the instant invention to provide a novel reflective screen barrier for circuit breaker arc chutes which is designed to completely de-ionize and cool exiting gases formed during an interrupting operation.

Another object of the instant invention is to provide a novel reflective screen barrier for circuit breaker arc chutes wherein the barrier is comprised of a corrugated reflective screen member.

Still another object of the. instant invention is to provide a novel reflective screen barrier for circuit breaker arc chutes wherein the barrier is comprised of a corrugated reflective screen housed in a compartment defined by upper and lower multi-apertured baflle plates.

Still another object of the instant invention is to provide a novel reflective screen barrier for circuit breaker arc chutes wherein the barrier is comprised of a corrugated reflective screen housed in a compartment defined by upper and lower multi-apertured bafiie plates wherein the apertures in said bafile plates are so positioned as to cause exiting gases to pass diagonally through the reflective screen, thus enhancing the cooling and de-ionization operation.

Another object of the instant invention is to provide a novel circuit breaker arrangement comprised of first and second circuit breaker contact pairs each having'a separate arc chute section associated therewith.

Another object of the instant invention is to provide a novel circuit breaker arrangement comprised of first and second circuit breaker contact pairs each having a separate arc chute section associated therewith, wherein the first and second arc chute sections are housed within a single compact shell .and are provided with a center wall having an opening providing communication between the two are chute sections. 7

Still another object of the instant invention is to provide a novel circuit breaker having first and second in dependent arcing contact pairs each having a complete independent arc chute associated therewith, wherein the center wall between the first and second arc chute sections is provided with an opening for communication between the sections and which spreads are interruption into both of said sections during a tripping operation.

Still another object of the instant invention is to provide a novel circuit breaker having first and second independent arcing contact pairs each having an independent arc chute section associated therewith wherein the center wall between said are chute sections is provided with an opening for communication between the sections and wherein each of said are chute sections is provided with a corrugated reflective screen barrier for rapidly cooling and de-ionizing exiting pases present in said sections.

These and other objects of the instant invention will become apparent when reading the accompanying description and drawings in which:

FIGURE 1 is an elevational view of a circuit breaker designed in accordance with the principles of the instant invention.

FIGURE 2 is an end view of the circuit breaker of FIGURE 1, wherein the lefthand phase is a sectional view of the breaker of FIGURE 1 taken along the line 2-2' and wherein the righthand phase shows the circuit breaker first and second cooperating contact sets in greater detail.

FIGURE 3 is a top view of the arrangement of FIG- URE 2.

FIGURE 4 is a top view of the circuit breaker of FIGURE 1 with the compartment roof removed.

Referring now to the drawings and more particularly to FIGURES 1 and 2, there is shown therein a circuit breaker arrangement '10 mounted by fastening means 11 and 12 to a vertical support means 13. The circuit breaker arrangement is provided with upper and lower disconnects 14 and 15 respectively, having star spacers 16 and 17 secured respectively thereto by the fastening members 18 and 19 respectively. The star spacers 16 and "17 act to position and secure finger contacts 20 and 21 which are further held against the star spacers 16 and '17 by means of garter springs 23-23 and 24-25 respectively. The finger contacts .are employed to engage the disconnects 14 and 15 at their right-hand ends and to engage the cooperating stationary disconnects 26 and 27 respectively, at their lefthand ends. The disconnects 26 and 27 are connected to the electrical circuit being protected by the circuit breaker assembly 10. A detailed description of the tulip clip primary contacts 20 and 21 with the star spacers 16 and 17, respectively, is fully set forth in copending application No. 45,153, entitled Tulip Clip Primary Contacts with Star Spacer filed July 25, 1960, by C. J. Yarrick et a1. and assigned to the assignee of the instant invention. For that reason, a detailed description of these contacts will be omitted, but it is suflicient to understand that the finger contacts 20 and 21 provide a suiable current path between the upper disconnect contacts 26 and 14 and the lower disconnect contacts 27 and 15 respectively.

The upper disconnect 14 is electrically connected to a main contact 28 and an arcing contact 29'wlhich is pivotally connected at 30 to disconnect 14. The lower disconnect 15 is provided with a contact 31 and is further pivotally connected at 32 to a movable bridge 33. Movable bridge 33 is provided with first and second main contacts 34 and 35 which are adapted to engage contacts 28 and 31 respectively and is further provided with an arcing contact 36 adapted to make contact with the stationary arcing contact 29. When in the closed or fully engaged position, the current path extends through 'lower disconnects 27, .15, contact 31 through contact 35 to contact 34 and contact 28 to the upper disconnects 14 and 26, thus completing theelectrical circuit. During the opening operation contacts 34 and 35 are adapted to become disengaged from theirassociated and 31 respectively, prior to the disengagement between the arcing contacts 29 and 36 so that any are formed during the tripping operation is formed between the separating arcing contacts 29 and 36. The pivotally mounted arcing contact 30 is urged against its cooperat ing arcing contact 36 by means of first and second helical springs 37 and 38 which act to keep the arcing contacts 29 and 36 in engagement beyond the time that the contact pairs 28-34 and 31-35 become disengaged.

The movable bridge 33 is operated between the engaged and disengaged position by a suitable prime moving means [not shown] which is coupled to rotate the hexagonal shaft 39. The hexagonal shaft 39 has keyed thereto a member 40, the upper end of which is pivotally connected at 41 to a coupling means 42, which is pivotally connected at its left-hand end 43 to movable bridge 33. Thus, with the circuit breaker in the position as shown in FIGURE 1, clockwise direction, as shown by arrow 44, member will likewise rotate in the counterclockwise direction urging coupling member 42 towards the left so as to pivot movable bridge 33 counterclockwise about its pivot point 32 causing the arcing contacts 29-36 and the main contacts 28-34 and 31-35 to come into engagement. By rotating hexagonal shaft 39 in the clockwise direction as shown by arrow 45, this rotational movement provides an opening or tripping operation The circuit breaker assembly 10 is further provided with an arc chute assembly positioned so as to aid in the rapid extinguishment of an arc drawn between the arcing contacts 29-36 during an interrupting operation. The are ohute assembly is provided with a plurality of spaced parallel arc plates 51, each of said are plates being provided with inverted substantially V-shaped notches 52 to provide suitable clearance for the movable bridge 33, the relationship between the elements 51 and 33 being best portrayed in FIGURE 2.

The are chute 50 is further provided with front and rear are runners 52 and 53 which are provided to receive the are formed during an interrupting operation which transfers from the cooperating arcing contacts 29 and 36 to the front and rear arc runners 52 and 53. Immediately above the interrupting chamber, which contains the front and rear arc runners 52 and 53 and the spaced parallel arc plates 51, is a mixing chamber 54, which chamber is defined by first and second baffle plates 55 and 55 which are arranged at the lower and pp SUI contacts 28 if shaft 39 is rotated in the counter faces, respectively, of the mixing chamber 54. The mixing chamber is further compartmentalized by means of vertical plates 57 arranged to form four separate compartments of mixing chambers above the interruption chamber. These vertical plates or partitions 57 can best be seen in FIGURE 2 of the drawings. The function of the mixing chamber is that of accumulating hot ionized gases which are moving rapidly in the upward vertical direction between the spaced parallel arc plates 51 so as to cause a combining action of the exiting gases in the compartments of the mixing chamber 54 in order to facilitate the cooling and de-ionization of the gases as well as a deceleration of the upwardly moving gases.

A reflective screen barrier chamber 58 is provided immediately above the mixing chamber 54. The reflective screen barrier chamber 58 is provided with a third baffle plate 59 which together with second baflle plate 56 defines the upper and lower surfaces of the reflective screen barrier chamber 58. Each of the baffle plates 56 and 59 are provided with a plurality of elongated apertures or slots which can be seen in FIGURES 3 and 4, wherein the slots 56a of bafiie plate 55 can best be seen in FIG- URE 3 and the slots 59a of bafile plate 59 can best be seen in FIGURE 4. Positioned between baifie plates 56 and 59 is a corrugated reflective screen barrier 60 which is formed of a metallic screen having its upper and lower vertices 60a and 60b respectively, resting against the upper and lower baflie plates 59 and 56 respectively. -It can be seen from a consideration of FIGURE 1 that the elongated slots 56a and baffle plate 56 are positioned so as to be between the lower vertices 60b of the corrugated reflective screen barrier 60, while the elongated slots 59a of bafile plate 59 are positioned so as to be between the upper vertices 60a. With this arrangement exiting gases enter into the reflective screen barrier chamber 58 through the elongated slots 56a.as shown by the arrows 61 and exit through the apertures 5942 as shown by the arrows 62. In order to exit through the apertures 590, the exiting gases must take a diagonal path through the corrugated reflective screen barrier 60 in the manner shown by arrows 63. This places the exiting gases in direct contact with the reflective screen 60. The mesh screen is formed of a metallic material which has a high thermal conductivity and which is further capable of absorbing considerable energy. Thus, contact between the exiting gases and the reflective screen 60 causes the exiting gases to be cooled and to be decelerated in their upward vertical movement. With the apertures 56a and 59a of baffle plates 56 and 59 respectively being positioned in the manner as shown in FIGURE 1, there is no direct line of slight exit for escaping gases to mrmit them to 'move in a straight line in the upward vertical direction. This arrangement thereby causes the upwardly moving gases to combine and admix to a very high degree which aids the cooling and de-ionization process and further to be slowed down considerably at the time they exit through the apertures 59a. In addition thereto, the provision of a corrugated arrangement with the reflective screen barrier 60 provides an extremely large surface area of screen many times greater than the width of the reflective screen barrier compartment 58 so as to provide an extremely large amount of cooling and deionizing surface for the exiting gases. ionization and cooling of exiting gases is so efiicient that a grounded roof 64 positioned above the arc chute 50 may be placed directly over the arc chute and in close proximity thereto allowing only for mechanical clearance between the arc chute 50 and the compartment roof 64. This close positioning is possible due to the fact that the gases are so cooled and de-ionized that no line to ground fault may occur through the medium of the gas.

In addition to the novel mixing and reflective screen barrier chambers 54 and 58 of the instant invention, the circuit breaker is further designed so as to have first .and second contact sets each of which are provided with The arrangement for defirst and second movable bridges 33 and 33' which movable bridges can best be seen in FIGURE 2. FIGURE 2 depicts a circuit breaker arrangement for the protection of a two-phase electrical system, wherein the first phase is provided with a circuit breaker assembly 10A and the second phase is provided with a circuit breaker 10B. While only two phases are shown herein, it should be understood-that a greater or lesser number of phases may be protected with the circuit breaker arrangements of the instant invention. The phase 10A, in addition to being provided with first and second separate and independent contact sets each being identical to the contact sets 29-36, 28-34 and 31-35 shown in FIGURE 1, is further provided with first and second arc chutes and 59 shown in FIGURE 2, each of said are chutes being identical to the arc chute 50 described in FIGURE 1.

The are chutes 5i) and 50' are housed in singled shell 70 and separated by a common wall 71 of the compact shell 70. While common wall 71 effectively separates arc chutes 5t) and 56 from one another, communication between the arc chutes 5i) and 50' is provided by means of an opening 72 in center wall 71, which opening 72 is provided for a purpose to be more fully described. The top surface of phase 10A, can best be seen in FIG- URE 3, wherein some of the parts have been removed for a purpose of clarity. For example, the arc chute 50 shows the top surface of the baffle plate which is provided with elongated apertures 55a, whereas thearc chute 50 shows the arc plates 51 in full view, the baffle plate 55 having been removed.

The operation of the multisection chute comprised of arc chute sections 50 and 50' is as follows:

Each phase 10A and 10B is so designed that its movable bridges, such as, for example, the movable bridges 33 and 33 of phase 10A which are coupled to the hexagonal shaft 39, are designed so as to rotate in synchronism with one another. This operation should provide that the cooperating arcing contacts 29-36 should become disengaged at the same time that the other contact pair 29'-36 become disengaged. However, as a practical matter, the disengagement of these contact pairs will not be in exact synchronism, but one of the two contact pairs will open a slight instant of time before the other. For example, let

it be assumed that during an opening operation the contact pair 29'-36 opens just prior to the separation of the contact pair 29-36. This means that with contact pair 29-36 still in engagement and with contact pair 29-36 separated ever so slightly, that a higher impedance path will exist between the contact pair 29'-36. Thus, no arc will be formed between contact pair 29-36' due to the extreme low current path through the contact pair 29-36. At the time that the contact pair 29-36 separates an arc will be drawn therebetween. Let it first be assumed that the interruption operation presently being performed is being performed during a low fault current condition. If separation between contact pair 29-36 occurs, the are drawn therebetween causes hot ionized gases to form. These gases will mainly be driven in the upward vertical direction through the arc chute section 50. However, certain of these gases will pass through the center wall opening 72 into the arc chute section 50'. Since the gases enter into the arc chute section 50' at a position fairly well above the cooperating contacts 29-36, these ionized gases will not cause an arc to be drawn between thesse contacts. However, any ionized gases entering into are chute section 50 will pass through the mixing chamber 54' and the reflective screen barrier chamber 58 so as to aid in the exiting operation of the upwardly moving gases which are formed in the arc chute section 50. Thus, the major portion of the gases will exit through the mixing chamber 54 and the reflective screen barrier chamber 58 of the arc chute section 50, but the operation nevertheless will be aided by the arc chute section 50'.

During extremely high fault current interrupting operations, however, even though one of the cooperating arcing contact pairs may open just slightly before the other of the two pairs such that an arc will only be drawn in one of the arc chute sections, the hot ionized gases which are formed in the chamber will be so intense as to completely fill the other are chute chamber o as to cause an arc to be struck between the cooperating contacts of the other are chute section. Thus, in the performance of an interrupting operation for the interruption of an extremely high fault current, both. separating arcing contact pairs 29 36 and 29-36 will form arcs therebetween and both arc I chute sections 50 and 50 will aid in the extinguishment of the arcs formed in the respective arc chute sections. However, in the case of an interruption operation for in terrupting low magnitude fault currents, only one of the arc chute sections will contain an arc and the section containing the arc will be randomly determined since no deliberate design has been provided in the circuit breaker assembly to cause one of the cooperating'arcing contact pairs to open before the other, but actually every etfort has been made to cause the movable bridges 33 and 33' to open in exact synchronism.

In order to provide for rapid movement of the arc upward through the arc chute sections 50 and d, the arc plates 51 of each arc chute section are formed of a conductive ferromagnetic material.

The operation of the arc plates 51 is as follows:

Let it be assumed that an arc is drawn between the front and rear arc runners 52 and 53 and occupies the position A as shown in the arc chute section 50 of FIG- URE' 1. The electric current are A sets up a magnetic field acting to magnetize the magnetic arc plates 51. The magnetic field set up in the arc plates 51 acts to pull the arc in the upward vertical direction. Once the arc occupies the position as designated by the numeral A of FIGURE 1, the arc is drawn between the arc plates 51 and the plates being of a conductive material act to rapidly cool the are A. The are A continues to move in the upward vertical direction due to the intense hot ionized gases which are likewise moving in the upward vertical direction. The baffle plate 55 and the vertical plates 57 forming the compartments of the mixing chamber 54 are formed of insulating material and prevent the are from moving upward out of the interrupting chamber which houses the spaced parallel arc plates 51. Thus, while the arc is substantially res-trained from moving above the interrupting chamber, the exiting gases nevertheless enter the mixing chamber 54 so as to go through a first stage of deionization and cooling and subsequently enter into the reflective screen barrier or chamber 58 wherein the hot ionized gases are almost totally de-ionized and cooled so that when they exit from the openings 59a in upper baflle plate 59 no danger of a restrike of the arc exists at this time. The reflective screen barrier chamber 53 is likewise compartmentalized by the vertical plates 73 provided therein so as to further enhance the mixing operation of the ionized gases entering into the reflective screen barrier chamber 58. All of the baifle plates 55, 56 and 59 as well as the vertical plates 57 and 73 are formed of insulating material so as to prevent an are from being drawn upon these elements.

The exiting gases which move upward from the mixing chamber 54 enter through the elongated openings 56a and bafile plate 56 and are momentarily restrained from any subsequent upward movement due to the presence of the corrugated reflective screen 60. This causes a further mixing and combining of the exiting gases in each of the triangular shaped regions defined by the corrugated screen 60. Subsequently, however, the gases still being urged in the upward direction begin to pass through the reflective screen barrier 60. In order to do so, the gases move in a diagonal direction as opposed to a straight upward vertical direction so as to first come into contact with the reflective screen 60 and so as, secondly, to be substantially decelerated in their upward movement. The extremely large surface area of the corrugated reflective screen 60 acts to rapidly cool and de-ionize the exiting gases so that as the gases escape through the elongated openings 59a and upper baflle plate 59 they are incapable of preventing any restrike of an are between live parts of the circuit breaker and the compartment roof 64 which may be safely grounded without any danger of enhancing the striking of an are between the live elements of the-circuit breaker and the compartment roof 64. In addition thereto, the compartment roof 64 is positioned in close proximity to the upper end of the circuit breaker arc chute 59 with the only clearance therebetween being provided for necessary mechanical clearance, thus substantially diminishing the height requirements of the circuit breaker compartment, the roof of which is designated by numeral 64.

It can, therefore, be seen that the instant invention provides a novel circuitbreaker assembly having a unique reflective screen barrier chamber providing highly effective de-ionization and cooling of exiting gases formed during an interruption operation. The circuit breaker is further provided with a multi-sectional arc chute assembly comprised of two substantially independent arc chute sections each being provided with interrupting, mixing and reflective screen barrier chambers being equally efiec tive in the cooling and de-ionizing exiting gases as well as extingushing arcs formed during the interrupting operation. The are chute sections, while divided by an inter- Althr-ough in the foregoing specification, the instant invention has been described in conjunction with preferred embodiments, many variations and modifications will now be apparent to those skilled in the art, and it is preferred, therefore, that this invention be limited not by the specific disclosure herein contained but only by the appended claims.

What is claimed is 1. Interrupting means for circuit breakers having a pair of cooperating contacts comprising an arc chute housing containing a plurality of spaced parallel arc plates positioned above the cooperating contacts to provide a tortuous path for an upwardly moving arc formed during a tripping operation; upper and intermediate horizontally aligned bafl-le plates positioned .at spaced intervals above said are plates for defining a first chamber; first vertical barrier means vertically aligned between said upper and intermediate baffle plates for compartmentalizing said chamber; said upper and intermediate baffle plates each having elongated slots aligned transverse to the length of said baflie plates to permit upwardly moving gases generated during a tripping operation to pass through said first chamber to undergo cooling and deionization; the slots of said upper and intermediate baflle plates being offset relative to one another .so that no direct :line-of-sight exists for associated openings of said upper and intermediate baflle plates, corrugated reflective screen means mounted within and along the length of said chamber; said upper and intermediate bafiie plates permitting the passage of gases into said chamber to be cooled and deflected by said corrugated reflective screen means; said corrugated screen means comprising a metallic reflective screen capable of dissipating a large amount of heat by radiation; the lower vertices of said corrugated screen means being aligned transverse to the length of said first chamber and engaging the surface of said intermediate baflle plate intermediate adjacent slots in said baffle plate; the upper vertices of said corrugated screen means being aligned transverse to the length of said first chamber and engaging the surface of said upper baffle plate intermediate adjacent slots in said upper bafiie plate to cause any gases moving upwardly through said chamber to strike said screen means and be deflected to move transverse to the vertical direction to facilitate the deionization and cooling of the gases.

2. The interrupting means of claim 1 further including a mixing chamber; said mixing chamber being comprised of a lower bafile plate horizontally aligned a spaced interval below said intermediate baflie plate to define said mixing chamber; said lower baffle plate having a plurality of elongated slots aligned transverse to the length of said intermediate baffle plate; the slots of said intermediate and lower baffle plates being olfset relative to one another so that no direct line-of-sight exists for associated openings of said intermediate lower baflie plates; said mixing chamber permitting the passage of gases into said first 15 chamber to be cooled and deflected by said corrugated reflective screen means.

References Cited by the Examiner UNITED STATES PATENTS 2,861,152 11/1958 Scully v r 200-144 3,005,892 10/ 1961 Yarrick 200-144 3,031,552 4/1962 Stewart 200-144 ROBERT K. SCHAEFER, Primary Examiner.

ROBERT S. MASON, KATHLEEN H. CLAFFY,

Examiners. P. E. CRAWFORD, Assistant Examiner. 

1. INTERRUPTING MEANS FOR CIRCUIT BREAKERS HAVING A PAIR OF COOPERATING CONTACTS COMPRISING AN ARC CHUTE HOUSING CONTAINING A PLURALITY OF SPACED PARALLEL ARC PLATES POSITIONED ABOVE THE COOPERATING CONTACTS TO PROVIDE A TORTUOUS PATH FOR AN UPWARDLY MOVING ARC FORMED DURING A TRIPPING OPERATION; UPPER AND INTERMEDIATE HORIZONTALLY ALIGNED BAFFLE PLATES POSITIONED AT SPACED INTERVALS ABOVE SAID ARC PLATES FOR DEFINING A FIRST CHAMBER; FIRST VERTICAL BARRIER MEANS VERTICALLY ALIGNED BETWEEN SAID UPPER AND INTERMEDIATE BAFFLE PLATES FOR COMPARTMENTALIZING SAID CHAMBER; SAID UPPER AND INTERMEDIATE BAFFLE PLATES EACH HAVING ELONGATED SLOTS ALIGNED TRANSVERSE TO THE LENGTH OF SAID BAFFLE PLATES TO PERMIT UPWARDLY MOVING GASES GENERATED DURING A TRIPPING OPERATION TO PASS THROUGH SAID FIRST CHAMBER TO UNDERGO COOLING AND DEIONIZATION; THE SLOTS OF SAID UPPER AND INTERMEDIATE BAFFLE PLATES BEING OFFSET RELATIVE TO ONE ANOTHER SO THAT NO DIRECT LINE-OF-SIGHT EXITS FOR ASSOCIATED OPENINGS OF SAID UPPER AND INTERMEDIATE BAFFLE PLATES, CORRUGATED REFLECTIVE SCREEN MEANS MOUNTED WITHIN AND ALONG THE LENGTH OF SAID CHAMBER; SAID UPPER AND INTERMEDIATE BAFFLE PLATES PERMITTING THE PASSAGE OF GASES INTO SAID CHAMBER TO BE COOLED AND DEFLECTED BY SAID CORRUGATED REFLECTIVE SCREEN MEANS; SAID CORRUGATED SCREEN MEANS COMPRISING A METALLIC REFLECTIVE SCREEN CAPABLE OF DISSIPATING A LARGE AMOUNT OF HEAT BY RADIATION; THE LOWER VERTICES OF SAID CORRUGATED SCREEN MEANS BEING ALIGNED TRANSVERSE TO THE LENGTH OF SAID FIRST CHAMBER AND ENGAGING THE SURFACE OF SAID INTERMEDIATE BAFFLE PLATE INTERMEDIATE ADJACENT SLOTS IN SAID BAFFLE PLATE; THE UPPER VERTICES OF SAID CORRUGATED SCREEN MEANS BEING ALIGNED TRANSVERSE TO THE LENGTH OF SAID FIRST CHAMBER AND ENGAGING THE SURFACE OF SAID UPPER BAFFLE PLATE INTERMEDIATE ADJACENT SLOTS IN SAID UPPER BAFFLE PLATE TO CAUSE ANY GASES MOVING UPWARDLY THROUGH SAID CHAMBER TO STRIKE SAID SCREEN MEANS AND BE DEFLECTED TO MOVE TRANSVERSE TO THE VERTICAL DIRECTION TO FACILITATE THE DEIONIZATION AND COOLING OF THE GASES. 